The general function of the meniscus or cartilage which separates the bones of the joint is to cushion and lubricate the joint. When the natural meniscus is damaged as the result of traumatic injury or deterioration, the natural meniscus is often removed surgically. In the absence of the meniscus, the bones of the joint are not properly positioned, cushioned or lubricated. Therefore stresses arise in the operation of the joint, the range of motion and flexibility of the joint can be restricted, and arthritis commonly develops in the joint.
In response to the problems which arise from the mere removal of the natural meniscus, total joint replacements have been proposed. As shown in U.S. Pat. Nos. 4,085,466; 4,224,696 and 4,224,697, such prosthetic joints generally include replacement of the articular surfaces of the bones as well as provision of a mechanical joint or other interface between the artificial articular surfaces. Such total joint replacements are subject to failure of the components or weakening of the bond between the bone and the implanted articular surfaces, and experience has shown that 20-30% of such replacements are ultimately unsuccessful. Furthermore, attempts to provide complete natural movement of joints such as the knee have led to the development of highly complex artificial joints.
U.S. Pat. No. 4,085,466 also suggests that a meniscal component can be made from a resilient plastic material and inserted alone between the natural femoral and tibial articular surfaces. It is further suggested that differential resilience be achieved in such an insert by making the insert in the shape of a disc and wrapping a sock of nylon or other synthetic fiber around the circumferential surface of the disc. However, no means is suggested for holding the disc in place within the joint.
Thus, there is a need in the art for a successful manner in which to avoid the problems of cartilage removal without resort to the complexity and post-operative complications of total joint replacement.